Catalytic Application of Cs‐Substituted Phosphotungstic Acid (CsxH3‐xPW12O40)‐Mesoporous Zirconium Phosphate (m‐ZrP) Nanocomposite Towards Synthesis of Structurally Diverse Tetrazole Moieties

Abstract The rational design of a high surface area heterogeneous nanocomposite catalyst with well‐defined surface acidic sites and structural porosity is a promising approach with potential application in expeditious synthesis of biologically active molecules/scaffolds. In this work, mesoporous zirconium phosphate (m‐ZrP) was synthesized through a hydrothermal process and used as a porous matrix for dispersion of cesium‐exchanged phosphotungstic acid (Cs x H 3‐ x PW 12 O 40 ) nanoparticles to prepare Cs x H 3‐ x PW 12 O 40 ‐mZrP nanocomposite systems. Various characterization techniques, including XRD, UV–vis‐DRS, FTIR, FESEM, HRTEM, TGA‐DTA, BET, and TPD, were used to understand the structural, morphological, and surface properties of the composites. XRD analysis revealed the presence of m‐ZrP and cubic Cs x H 3‐ x PW 12 O 40 crystalline phases in the nanocomposite materials. A microscopic study indicated the existence of rod‐shaped morphology that was formed by the coalescence of a large number of spherical nanoparticles with diameters between 150 and 200 nm. The dispersion of Cs x H 3‐ x PW 12 O 40 over the m‐ZrP surface results in significant enhancement of medium and strong acidic sites, with the maximum number of acidic sites observed for the Cs 0.5 ‐PTA‐mZrP composite (0.406 mmol g −1 ). The catalytic activity of the Cs x H 3‐ x PW 12 O 40 ‐mZrP nanocomposites was evaluated for rapid synthesis of tetrazole derivatives through [3 + 2] cycloaddition reactions of substituted nitrile and NaN 3 under mild conditions. The detailed optimization study revealed that the use of Cs 0.5 ‐PTA‐mZrP catalyst in DMF media afforded 90% yield of the tetrazole at 120 °C. Reaction kinetics study suggested that the optimal Cs 0.5 ‐PTA‐mZrP catalyst exhibited the highest reaction rate of 2.06 × 10 −3 mmol h −1 m −2 towards tetrazole formation. Structurally diverse tetrazole derivatives in high yield and purity were synthesized under mild conditions using Cs x H 3‐ x PW 12 O 40 ‐mZrP nanocomposite as catalyst.